<!DOCTYPE html>
<html>
<head>
	<title></title>
	<script type="text/javascript" src="./js/observer.js" ></script>
</head>
<body>
<div id="test"></div>
<script type="text/javascript">
	var obj = {
		a: 1,
		b: 2,
		c: 3
	}
	Object.keys(obj).forEach(function(key){
		new Observer(obj, key, obj[key])
	});
	new Watcher(function(){
		document.querySelector("#test").innerHTML = obj.a;
	})
</script>
</body>
</html>